This invention relates to an automotive vehicle door lock assembly for automatically locking and unlocking a door manually as well as electrically using a miniature motor.
A door lock assembly of this type is disclosed in e.g. the specification of Japanese Utility Model Publication (KOKOKU) No. 54-30317 (hereinafter referred to as "the former") and the specification of Japanese Patent Application Laid-Open (KOKAI) No. 57-68480 (hereinafter referred to as the "latter").
As shown in FIG. 14, the former discloses an arrangement in which a reduction gear unit 30 has a stroke larger than a stroke distance L of an operated lever 31 on both sides of a neutral position. The gear reduction unit 30 and the operated lever 31 are connected via connecting means 32 having play 32a equivalent to the stroke distance L of the operated lever 31. Also provided is a spring 33 biasing the gear reduction unit 30 in the neutral position.
As shown in FIGS. 15 and 16, the latter discloses an arrangement including an intermediate reduction gear 43 meshing with a pinion 42 of a motor rotary shaft 41, and an intermediate pinion 46 meshing with a rocking gear 45 connected to an output shaft 44 for operating an operated lever 50 of the door lock proper. The intermediate reduction gear 43 and intermediate pinion 46 are supported on the same shaft and are provided so as to be freely engagable via a resilient body 47 through rotational play and an angle which correspond to the stroke of the operated lever 50. After the assembly is locked and unlocked by a motor 40, the intermediate reduction gear 43 is reversed by the resilient body 47.
The former door lock assembly has a structure in which lost motion is allowed to occur at an oblong hole 32a provided at the portion where the connecting means 32 and lever 31 are connected. Consequently, it is required that the gear reduction unit 30 have a stroke which is about twice the stroke length L of the operated lever 31. As a result, the door lock assembly is large in size. Furthermore, since the spring 33 constantly subjects the motor to a rotational load, motor loss is great and a high-output motor is required.
The latter door lock assembly has a structure in which the intermediate speed reduction gear 43 inclusive of the motor rotary shaft 41 is restored to the neutral position by the restoration force of the resilient body 47. Consequently, if there is a drop in the operating voltage or an increase in the turning resistance of the shaft portions due to the passage of time or the like, the intermediate reduction gear 43 will not readily return to the neutral position and it will be required that the user apply a greater operating force when the door lock is operated manually.
The aforementioned drawbacks of the prior art constitute a first problem to be solved by the present invention.
Accordingly, a first object of the present invention is to provide a door lock assembly which solves the aforementioned problem encountered in the prior art, specifically a structurally simple and compact door lock assembly capable of performing a locking and unlocking operation with application of a small operating force when the door lock is operated manually as by a locking button or key.
A further description of the door lock assembly disclosed in the abovementioned Japanese Patent Application Laid-Open (KOKAI) No. 57-68480 will be given with reference to FIG. 17. Here the door lock assembly is shown to comprise a locking arm 231 freely rockably connected to a door lock operating unit 230, an actuator 232, and a combination of a rocker arm 233 and connecting rod 234 for transmitting the output of the actuator 232 to the locking arm 231.
Owing to vehicle design and space limitations, the actuator 232 for performing an electrical locking and unlocking operation in this conventional door lock assembly is provided at a position comparatively far from the door lock operating unit 230. Accordingly, the arrangement is such that the output of the actuator 232 is transmitted to the locking arm 231 via such elements as the rocker arm 233 and connecting rod 234. This requires a large number of component parts and, hence, higher cost. In addition, assembling the door lock is difficult because the actuator 232 and door lock operating unit 230 are separate elements. If the door lock assembly has a self-cancelling mechanism, moreover, the heavy connecting rod 234 will impede the unlocking operation or, because of its inertia, will fall back into its former position once the assembly has been unlocked, thereby inadvertently restoring the locked state. Thus, this arrangement is prone to erroneous operation. These disadvantages constitute a second problem to be solved.
Accordingly, a second object of the invention is to provide a compact door lock assembly that does not employ a connecting rod.
Another example of a conventional door lock assembly of the abovementioned type is disclosed in the specification of Japanese Patent Application Laid-Open No. 59-109678. When this conventional door lock assembly is locked and unlocked automatically, a rotational member formed to include a spirally shape cam groove is rotated by a motor so that a follower engaged with the cam groove is moved from a neutral position of the cam groove to the end thereof to be rocked about a bolt, whereby a lock/unlock member operatively associated with the follower is caused to undergo rocking motion to establish a locked or unlocked state. After the assembly is locked and unlocked, the rotational member is restored to the neutral position by the biasing force of a coil spring. When this conventional door lock assembly is locked and unlocked manually, the lock/unlock member is rocked manually to establish the locked and unlocked state when the rotational member is in the neutral position, namely when the follower is in a position within the cam groove at which it can be rocked to an extent that will enable the assembly to be locked and unlocked.
If the rotational resistance of the rotational member in this conventional door lock assembly increases to such an extent that the rotational member is no longer restored to the neutral position by the biasing force of the coil spring, the follower will no longer be capable of rocking far enough to place the door lock assembly in the locked and unlocked states due to the wall of the cam groove. Consequently, the lock/unlock member will not be capable of being rocked manually to place the door lock assembly in the locked and unlocked states. This is a third problem to be solved by the invention.
Accordingly, a third object of the present invention is to provide a door lock assembly in which the locked and unlocked states can be attained both automatically and manually even if the rotational member is not restored to the neutral position.